
Receiver Calibration

Each receiver model has different characteristics of output voltage versus
input deviation and output voltage versus input signal strength.  A set of
generic calibration curves is provided for all of the supported radios.
These curves were derived from a (relatively small sample) of radios available
to the developers so may not represent your specific receiver.

Within a model, each receiver is slightly different and can be calibrated to
provide best performance.  The following procedure describes how to derive a
substitute calibration curve for the generic one supplied.


Equipment needed:
TxID-1 Card and Software
modified Receiver (with Discriminator and Signal Strength outputs)
Station Monitor (IFR 1500 or equivalent)

Set-Up
Install the TxID-1 Card, Software, and Receiver normally.
Connect the Station Monitor RF output to the receiver antenna input.
Tune both the receiver and the Station Monitor to the same frequency and set
the Signal Strength to your group standard.  (-70 dBM seems to work pretty
well.  All of the generic radio calibrations have been performed at that
level.)

Start up the TxID Software and execute the  (T)est option

Procedure:
Deviation Calibration:
Initiate the  (D)eviation sub-function on the test menu
Note the hexadecimal value on the attached chart for the center frequency.

For eight steps both + and - 1 KHz (that is, from center frequency - 8 KHz
to center frequency + 8 KHz), tune the Station Monitor to the appropriate
offset, wait for a second or two until the values stabilize, read the Hex
value off the screen, and enter into the chart.

When done, press any key to terminate the test.

Signal Strength Calibration:

Initiate the  (S)ignal Strength sub-function on the test menu
Note the frequency at which teh calibration is performed..

Tune the station monitor to the signal strengths noted on the chart (from
-128 dBM to 0 dBM, i.e. -128, -120 dBM and 10 dBM steps to 0).  After setting
the signal strength, wait for a second or two until the signal settles, read
the hex value and write into the appropriate space on the
chart.

When done, press any key to terminate the test.

Compute the deltas between readings and enter into the charts.  If any
adjacent deltas are the same, cross out the middle value.

Create an ASCII text file named for the specific radio that is being
calibrated.  The first three characters designate the manufacturer and model
(R70 for the ICom R7000, R71 for the ICom R7100, AR3 for the AOR AR-3000(A),
etc.).  The last five characters are the serial number of the radio.  The
extension is  ".CAL"  for calibration data.
  
The first line of the file should be a comment (starts with an  "*" 
(asterisk)) and denotes the make/model, the serial number, the chosen center
frequency at which the measurements were made, the signal strength at which
the deviation measurements were made, the date and operator's initials.
The second line should be an annotation command  (prefix  "AAR")  followed by
the make and model and serial number.
The third line is the Deviation Calibration data  (prefix  "VAD")  followed by
pairs of hex values from the chart.  Each pair is separated by a comma.  The
pairs are separated from each other by a  ";"  (semi-colon).  The first value
in the line is from column  "(Deviation) Value" and the second is from the
corresponding line  "Nominal".  The first values of each pair must be
increasing in size.  (That is, if the slope of the deviation is negative,
start at the bottom of the chart.)
The fourth line is the Signal Strength Calibration data  (prefix  "VAS"  and
consists of pairs of values similar to the Deviation but the first value is
from the "(Sig Str) Value" column and the second is from the "(Sig Str)
Nominal" column.  Remember that the first values of the pairs must be
increasing in value.


Usage:
Add a line into your  TxID.CFG  file that reads:

             /<filename.CAL>

E.g.

             /R7103028.CAL

This will cause the TxID Software to use your new calibration data the next
time it is started.

TxID-1 Receiver Calibration
Date _______________
Remarks _________________________________________________________
        _________________________________________________________
        _________________________________________________________
Receiver       Mfg/Model _________________  S/N ______________
Test Equipment Mfg/Model _________________  S/N ______________
TxID-1  S/W Ver _________ Date _________ F/W Ver______________

Center Frequency ________________ MHz   Sig Str ________dBM

Deviation						    Signal Strength
Freq  Value  Delta  Nominal         dBM    Value  Delta  Nominal
 (KHz)        (Hex)  (Hex)         (dBM)         (Hex)  (Hex)  (Hex)
  -8  _____           00           -128   _____           00
             _____                               _____
  -7  _____           10           -120   _____           10
             _____                               _____
  -6  _____           20           -110   _____           24
             _____                               _____
  -5  _____           30           -100   _____           38
             _____                               _____
  -4  _____           40            -90   _____           4C
             _____                               _____
  -3  _____           50            -80   _____           60
             _____                               _____
  -2  _____           60            -70   _____           74
             _____                               _____
  -1  _____           70            -60   _____           88
             _____                               _____
   0  _____           80            -50   _____           9C
             _____                               _____
   1  _____           90            -40   _____           B0
             _____                               _____
   2  _____           A0            -30   _____           C4
             _____                               _____
   3  _____           B0            -20   _____           D8
             _____                               _____
   4  _____           C0            -10   _____           EC
             _____                               _____
   5  _____           D0              0   _____           FF
             _____
   6  _____           E0
             _____
   7  _____           F0
             _____
   8  _____           FF

VAD___,___;___,___;___,___;___,___;___,___;___,___;___,___;___,___;

   ___,___;___,___;___,___;___,___;___,___;___,___;___,___;___,___

VAS___,___;___,___;___,___;___,___;___,___;___,___;___,___;___,___;

   ___,___;___,___;___,___;___,___;___,___;___,___


                    ICD for a FINGERPRINT
                        K7PF  09/26/93
                        N7SNI 07/03/94

The intent is to provide a simple, flexible format for data which is used to
identify a transmitter, and define a minimum format which contains the basic
data needed by all users.

Prior to the formatted data, a synchronization pattern which depends on the
method of transmission is needed.  For example: audio tape is written using
synchronous coding (no start/stop bits) at 1000 bits/sec, where sync
consists of four zero bytes followed by a single A5 hex byte.  Radio
transmission uses start/stop (UART) coding at 9600 bits/sec, and sync consists
of five 5A hex bytes followed by a single A5 hex byte.

The storage format for a minimum fingerprint is as follows:

64 bytes of processed frequency versus time data (common to all formats)
1 byte of bytecount (format#)
4 bytes of frequency (packed BCD)
3 bytes of date (packed BCD)
3 bytes of start time (packed BCD)
      * during Remote transmission, data up to here is transmitted first
3 bytes of end time (packed BCD)
1 byte of received signal strength
1 byte of peak deviation (zero if not available)
1 byte of DTMF deviation (zero if not available)
2 bytes of Sub-Audible (CTCSS tone number in first byte if MSB is zero/
3 nybbles of DCS Code if MSB is one)
1 byte of Sub-Audible deviation 62.5*Hz (zero means no Sub-Audible)
1 byte of checksum
-----
84 bytes total

2 bytes of Bearing (0000= 0 degrees/FFFF= 360 degrees) (LSByte first)

Detailed data descriptions of each hex (or BCD) quantity follow:
byte#               description of byte(s)
0-63      00h = -8 kHz
          80h = on frequency
          FFh = +8 kHz
          Assume 16 amplitude steps/kHz with byte samples spaced
          3.2 mS in time, for a total data duration of 204.8 mS
 64       Total bytecount to checksum 53h for this format)
 65       BCD center frequency: 1000 MHz, 100 MHz
 66       BCD center frequency: 10 MHz, 1 MHz
 67       BCD center frequency: 100 kHz, 10 kHz
 68       BCD center frequency: 1 kHz, 100 Hz
69-71     BCD date digits: month, day and year
72-74     BCD start time digits: hour, minute, second
75-77     BCD end time digits: hour, minute, second
 78       Signal amplitude (dependent on receiver)
 79       Voice peak deviation (1/16ths of kHz)
 80       Touchtone peak deviation (1/16ths of kHz)
 81       Sub-Audible tone
          00h = unknown code (e.g. 88 repeater)
          0mh = m is the CTCSS code number  (1 <= m <= 38)
          Fnh = n is Digital Control Squelch octet 1 (of 3)
 82       DCS octets 2 and 3
          Sub-audible envelope detector for 88 (>=50)
 83       Sub-Audible deviation (zero means no Sub-Audible tone)
          (1/16ths of kHz Peak to Peak divided by 2)
84-85     BCD Bearing Clockwise from North to Transmitter
          MSH of byte 84 is 100's of degree with MSB set
          digits.  (If byte 84 is zero, no bearing is available
86-94     BCD Location of Receiver Cdddmm.mmmmddmm.mmmm where byte 86 is a
          code {0=no pos,80=N lat,82=S lat} and {80=W Long while 84= East
          Long} and the 100's digit of longitude {000=Greenwich,100 is 100
          degrees west
     OR
86-mm     88 Repeater parameters
 xx       Eight bit CHECKSUM starts with fingerprint (sums to 0)
95        Reserved
96        Low Pass Filter Frequency (10's of Hz) (0->15->150Hz)
97        Length of FingerPrint (milliseconds) (0->204)
98        Length of time prior to Fast Squelch (milliseconds)
99        MSB set for Trailing edge (FCC proprietary)
          5 LSBs channel (0-7 from A/D; 8=Fast Squelch counts (A4->B4);
               9=Radio Squelch Counts from A0 to B0)
100-127   Ident/comment field, added by receiving or editing program.
          Bytes 87-127 are not recorded onto tape.
          (For GATHERFP ("GatherFP c<channel>{L=1 channel Leading edge;
          l=2 channel leading edge;T=1 channel trailing edge (FCC 
          proprietary);t=2 channel trailing edge FCC Proprietary)} 
          S<FingerPrint length> O<length before Fast Squelch(msec)>
          @XX " where XX is position in Raw data file of start of Fast
          Squelch.
